<!-- uppercase管道，让前面的值全部大写 -->
<div *ngIf="hero">
  <h2>{{hero.name | uppercase}} Details</h2>
  <div><span>id: </span>{{hero.id}}</div>
  <div>
    <label>name:
      <input [(ngModel)]="hero.name" placeholder="name"/>
    </label>
  </div>
</div>
<button (click)="goBack()">回到上一页</button>
<button (click)="save()">保存</button>
